Process for preparing



March 1964 L. E. LEFEVRE ETAL 5 2 5 PROCESS FOR PREPARING FILAMENTARYARTICLES 0F INVOLUTE CROSS SECTION Filed July 21, 1960 INVENTORS.

tloya'. efevre F/oyaE. Romesberg Gare/0'44. Hon

HGENT United States Patent 0."

3,126,699 PROCESS FOR PREPARING FILAMENTARY ARTICLES F INVOLUTE CROSSSECTION Lioyd E. Lefevre, Bay City, and Floyd E. Romesberg and Gerald M.Hart, Midland, Micln, assignors to The Dow Chemical (Iornpany, Midland,Mich, a corporation of Delaware Fiied July 21, 1960, Ser. No. 44,390 13Claims. (Cl. 57-460) This invention relates to a process for preparingnovel filamentary articles generally of cylindrical outline. Moreparticularly, it relates to such a process for preparing suchfilamentary articles from fiat tapes or ribbons. Still further, theinvention comprehends the novel filamentary articles so produced.

Cylindrical filaments are traditionally the most common structurefinding use in the manufacture of woven and unwoven articles. However,the preparation of solid fibers and filaments of such structure involvescomplicated spinning procedures requiring delicate control. Also, whenmade from synthetic, resinous material, these filaments result ingenerally poor fabric stability, especially in the looser weaves. It isalso commonplace to prepare hollow cylindrical filaments for specialeffects. The preparation of these hollow filaments is usually morecomplicated procedurally than the preparation of solid cylindricalfilaments. Because of these known production problems, there has beencontinuous search for improvements in the processes for preparing fibersand filaments.

It is known that flat tapes and ribbons may be laterally rolled into afilamentary structure. For example, U.S. 2,335,190, issued November 23,1943, to H. D. Minich, discloses a process wherein a flat tape of aresinous material, specifically rubber hydrochloride, is passeddiagonally across a heated roll and caused to roll up into a generallycylindrical monofilament. This process is sub ject to several proceduraldisadvantages from a practical viewpoint. In that process the individualfilaments tend to whip back and forth on the roll. To prevent contact ofthe filaments during rolling requires a wide separation between theindividual filaments on the roll and, consequently, results in a limitedproductive capacity for that roll. In addition to that disadvantage, ithas been found that reproducibility of the filaments prepared by thatprocess is not always of acceptable standard for use in weaving closelywoven fabrics. It would be desirable to have an improved process forpreparing rolled monofilaments from flat tapes or ribbons which processwould overcome the problems and disadvantages inherent in that patentedtechnique.

Accordingly, it is the principal object of this invention to provide animproved process for preparing filamentary articles by laterally rollinga tape or ribbon.

It is a further object to provide such a process whereby a plurality oftapes while in the close proximity may be rolled simultaneously.

It is a still further object to provide such a process whereby positiverolling forces are brought to bear against the flat tape.

Another object is the provision of such a process utilizing organic,thermoplastic, resinous materials,

Yet another object is the provision of such a process whereby a fibrousor filamentary core material may be inserted into the center of therolled filamentary article.

An associated object is the provision of novel, oriented filamentaryarticles of involute cross section.

The above and related objects are accomplished by means of the processcomprising the passage of a continuous, coherent, unoriented ribbon ofan organic, thermoplastic, resinous material in fiat, undistorted forminto first guide means, removal of said ribbon from said ice first guidemeans so that a plane through the longitudinal axis of said ribbon andperpendicular to the width of said ribbon is at an acute angle to anextension of said plane of said ribbon entering said first guide means,the passage of said ribbon through a second guide means disposedparallel to said first guide means so as to divert or to deflect saidribbon into a direction of travel substantially parallel to and finitelydisplaced from said plane of said ribbon entering said first guide meanswhile imparting a torque to said ribbon between said first and secondguide means to cause said ribbon to roll into a filament of an involutecross section having the original edges of said ribbon essentiallyparallel to the longitudinal axis of the filament and while maintainingsuflicient tension on said filament throughout the process to impartthereto orientation parallel to the longitudinal axis of said filament.The objects are further realized and attained with the orientedfilamentary article so produced.

The tapes useful in the present method may be of any organic,thermoplastic, resinous material. As materials which may beadvantageously used are the normally crystalline polymeric materials.These are the polymers which have a tendency to form crystallites orsites where small segments of a plurality of the polymer chains areoriented and held in position by secondary valence forces. Thiscrystallite formation or crystallinity is usually visible when thepolymers are examined by X-ray diffraction. Typical of the normallycrystalline polymeric materials falling within the advantageousdefinition are the polymers and copolymers of at least 70 percent byweight of vinylidene chloride with the remainder composed of one or moremonoethylenically unsaturated cotnonomers exemplary of which are vinylchloride, vinyl acetate, vinyl propionate, acrylonitrile, alkyl andaralkyl acrylates having alkyl and aralkyl groups of up to about 8carbon atoms, acrylic acid, acrylamide, vinyl alkyl ethers, vinyl alkylketones, acrolein, allyl esters and ethers, butadiene and chloroprene.Known ternary compositions also may be employed advantageously.Representative of such polymers are those composed of at least 70percent by weight of vinylidene chloride with the remainder made up of,for example, acrolein and vinyl chloride, acrylic acid andacrylonitrile, alkyl acrylates and alkyl methacrylates, acrylonitrileand butadiene, acrylonitrile and itaconic acid, acrylonitrile and vinylacetate, vinyl propi onate, or vinyl chloride, allyl esters or ethersand vinyl chloride, butadiene and vinyl acetate, vinyl propionate, orvinyl chloride and vinyl ethers and vinyl chloride. Quaternary polymersof similar monomeric composition will also be known. It has been foundthat the normally crystalline copolymers composed of from about 92 to 99percent by weight of vinylidene chloride and correspondingly from 8 to 1percent by Weight of acrylonitrile or of a lower alkyl acrylate havesuitable polymerization characteristics, are well adapted for use in themanipulative steps in this process, and result in exceptionally usefulfilamentary articles. For these reasons these vinylidenechloride-acrylonitrile and vinylidene chloride-lower alkyl acrylatecopolymers represent a preferred species for use herein. It should beunderstood, however, that the process is not limited to the treatment ofnormally crystalline polymers but that any non-elastic polymeric material may be employed. There are manymaterials, such as polyvinylchloride and the polystyrene, which are capable of forming continuous,coherent articles which are orientable but do not normally formcrystallites. The polymeric materials, Whether crystalline ornon-crystalline, may also include minor amountsof monomers, such asvinyl pyrrolidone, vinyl oxazolidinone, vinyl alkyl oxazolidinone, andthe like, which are known to aid the dyereceptivity and other propertiesof fibrous materials. Likewise, polymers containing interpolymerizedlight and heat stabilizers may be used. Also operable in the presentmethod are tapes of polymeric materials, such as the polyolefins,including, for example, polyethylene, polypropylene, copolymers ofethylene and propylene, and polyisobutylene. Equally useful in themethod are the condensation polymers, such as the polyamides, includingpolyhexamethylene diadipamide, and the polyesters, includingpolyethyleneterephthalate. Also of utility are the tapes and ribbons ofrubber hydrochloride, regenerated cellulose, synthetic cellulosederivatives, including cellulose esters, such as cellulose acetate, andcellulose ethers,

such as methyl cellulose and hydroxypropyl methyl cellulose. It shouldbe apparent that any organic, thermoplastic, resinous material which iscapable of being formed into a flat tape or ribbon will find utility inthe present invention.

The useful tapes for the present method are flexible tapes usually ofabout 0.001 to 0.005 inch in thickness and of about 0.1 to 1 inch inwidth. The thickness and width to be used in any given instance willdepend in large measure upon the end product desired and upon theshaping apparatus used. The above limits are those which would normallybe associated with the manufac ture of fibers and filaments. When it isdesired to make filamentary articles of greater size than, for example,about 0.3 inch diameter, it would usually be found desirable to employother techniques since wide sections of tape, which are more accuratelyreferred to as films, are not handled conveniently in the presentprocedural steps. However, it should be understood that the process isnot limited precisely to the l-inch maximum, since useful articles maybe prepared herefrom, although with less control of filament dimensionsthan with the narrower tapes.

The tapes or ribbons useful in the process may be prepared by knownplastics fabrication techniques. For example, a dry formulation of thepolymer may be thermally extruded directly into the tape or ribbon orinto a film which is subsequently slit into the desired tape or ribbon.Another fabrication procedure involves the preparation of the tapes orribbons directly or of a film which may be slit into the tapes orribbons. In this procedure a latex is deposited on a substratum and thendried into the film or the film may be formed by the continuous,localized coagulation of the latex followed by drying and fusing. Othersolutions and dispersions may be cast, precipitated, or coagulated intothe tapes or ribbons or into films from which the ribbons may be slit.Such fabrication techniques are well known in the plastics art. It isonly necessary for the present invention that the tape or ribbon befused and unoriented. By fused it is means that the tape or ribbon is,in the sense accepted in the plastics field, completely homogeneous andintegral as contrasted with the partial coalesced state of a dried butunbaked film of a latex of a polymer which is relatively hard. Byunoriented it is meant that the tape or ribbon has not been subjected tothe unilateral longitudinal stress which tends to align the individualmolecules in the direction of the major axis of the tape or ribbon.

The advantages and benefits of the present invention, as well as theoperation of the process, will be more apparent from the followingdescription and the appended drawings which are illustrative of apreferred embodiment of the process and of an apparatus useful forcarrying out the process.

In the drawings:

FIGURE 1 illustrates in schematic outline a procedural sequence to befollowed in carrying out the process and an apparatus useful therein,

FIGURE 2 represents a cross section of a typical rolled filament,

FIGURE 3 illustrates a cross section of a rolled filament of generallyoval or elliptical peripheral outline,

FIGURE 4 represents a cross section of a rolled filament having a solidmonofilamentary core, and

FIGURE 5 represents the point in the procedural sequence wherein a corematerial may be inserted into the rolled filament.

In the embodiment illustrated in FIGURE 1 a fused but unoriented tape orribbon 10 is fed from a suitable inventory (not shown) through a guidemeans 11 which may take the form of a comb, grooved roll, or otherconventional device. The tape 10 then passes about snubbing rolls 12into a groove located in first grooved roll 13. Following the groovedroll 13, the tape it} next passes over a second grooved roll 14 solocated as to deflect the path of travel of the tape 10 as it leavesroll 13. Following grooved roll 14, the tape or ribbon passes over asecond pair of snubbing rolls 15 operated at a peripheral speed greaterthan that of snubbing rolls 12 so as to impart a continuous orientingstress on the tape 10 as it passes through the shaping steps. Followingsnubbing rolls 15, the tape 10 is passed to suitable collecting means16, such as a conventional winding frame. It will be appreciated that,although only one tape is illustrated in FIGURE 1, the process isadaptable to the simultaneous treatment of a plurality of tapes arrangedparallel to each other.

The string-up for a plurality of ends is easily accomplished if thesecond grooved roll 14 is mounted on its shaft so as to be laterallyadjustable. In this case the grooves in rolls 13, 14 may be alignedduring string-up and the second roll 14 subsequently adjusted to thedesired lateral deflection. In addition, by having second roll 14laterally adjustable, minor changes in deflection may be accomplishedwithout stopping the process.

As shown, the present process requires the use of at least two groovedrolls or their equivalent. It has been found that the function of thegroove in each roll is different from its counterpart in the other rolland that, as a result, the shape of the groove in one roll that providesoptimum results is different from that in the other roll. In the firstgrooved roll 13 the grooved design is preferably of a shallow U shape.The function of this groove is to prevent the tape or ribbon fromveering from its normal path of travel until rolling commences and italso gives one edge of the tape a start toward rolling when it isdeflected from its original path of travel.

The preferred groove design for grooved roll 14 is deeper than that ofthe first grooved roll and is of a V shape having a rounded bottom. Thefunction of this groove in roll 14 is to impart a torque action on thetape as it is passed through the groove under the orienting stress. Therounded bottom prevents distortion of the shape of the newly formedfilament.

With most organic, thermoplastic materials it is preferred to heat eachof the rolls. For the normally crystalline vinylidene chloride polymersit has been found to be preferable to employ temperatures on the firstroll of from about 60 to 75 C. The heated first roll tends to soften thetape somewhat and facilitates the subsequent rolling. With thispreferred class of polymeric materials it is preferred to heat thesecond roll to from about 75 to C. to set the rolled configurations.Useful temperatures with other polymeric materials will be known or maybe easily determined by simple preliminary experiment.

As shown and mentioned in the illustrated embodiment, the roll isimparted to the tape by the use of offset grooves in rolls. The amountof offset may be varied within certain limits. In general, it may bestated that the greater the amount of offset or of deflection of thetape the more tightly rolled will be the resulting filament. As ageneral guide, it will be found that an offset of from about to inch maybe employed to produce the rolled filaments of this invention.

It has been also found that the width of the tape used should be nogreater than the groove opening. If the tape width is greater, therolling action is poor, erratic, and unreproducible. However, tapewidths equal to or less than the width of the groove opening exhibit thecontrolled rolling action that results in useful filamentary articles.If it is desired to increase the denier, it is possible to superpose twoor more tapes or ribbons upon one another and pass them simultaneouslythrough the same groove sequence. In regard to denier it should beapparent that the process is readily adaptable to the production of awide range of deniers of from about 100 denier or less, up to 2,000denier or greater. The denier may be varied by the choice of organic,thermoplastic, resinous material, the width and thickness of the ribbon,and the core material. Also, denier may be lowered by hot stretching thefilaments to a fraction of their original dimensions.

It is imperative in the preparation of the filaments that an orientinglongitudinal stress be applied to the tapes or ribbons during theshaping process. This aids in the rolling and in the setting of therolled cross section.

It has been found that the tightness of the rolling exerts an influenceon the cross-sectional outline of the filament. Loosely rolled filamentstend to be flattened by the subsequent snubbing action into a crosssection similar to that of FIGURE 3. Tightly rolled filaments retain thecylindrical outline, such as that of FIGURE 2.

In a special embodiment of the process a core material is inserted intothe center of the rolled monofilament, as illustrated in FIGURES 4 and5. This core material may be a monofilament, a yarn, or any othercontinuous filamentary structure. The chemical composition of the corematerial may be the same or different than that of the rolled filament.The core material may be orientable or non-orientable. Thus, solidcylindrical monofilaments of thermoplastic, resinous materials, such asvinylidene chloride polymers, polystyrene, polyvinyl chloride, polyvinylacetate, and other well-known thermoplastic materials, may be used asthe core. Likewise, fibers and filaments of polyacrylonitrile, nylon,polyethylene, and glass may be employed. The choice of core materialwill depend to large extent upon individual preference and on thecontemplated end use of the composite filament.

The core material is conveniently and advantageously inserted into therolled filament at the point of first deflection of the tape or ribbonfrom the first grooved roll. This is illustrated in FIGURE 5 where thetape is passing through a groove in roll 13 and, as it leaves roll 13, acore material 17 is laid against the tape as it is starting to curl. Ithas been found to be highly desirable to have at least two layers of thetape or ribbon surrounding the core material.

The process of the present invention permits the preparation of therolled filamentary articles with or without a core material. Thisprocess results in several benefits. First, it is capable of continuousoperation and is adaptable for fitting into an integratedfilament-making scheme that would include the tape or ribbon-makingprocedural sequence immediately preceding the present process. Therolled filaments resulting from this process are characterized generallyby a higher tenacity and a better hand than the tapes or ribbons fromwhich they' are formed. In addition, the rolled filaments arecharacterized by uniform cross-sectional dimensions and denier and bythe absence of any fray'ed, uneven, or torn edges as would be present inthe flat tapes or ribbons. The process is capable of producing rolledfilaments of generally round or oval or elliptical section. The processadapts itself to the production of rolled filaments of a wide variationin denier. Likewise, rolled filaments of any useful filamentarydimensions may be prepared. The process is adaptable without majorretooling to a wide diversity of thermoplastic materials. Many otherbenefits or advantages will be apparent to the skilled worker.

The tapes or ribbons utilizable in the process may contain the commonand conventional additives employed in polymer formulation. Theseinclude typically colorants, such as dyes and pigments; light and heatstabilizers; antioxidants; fillers; and others. These may be in 6corporated prior to the fabrication of the tape or ribbon, or, whenpossible, included by impregnation or other known means into theresultant rolled filament.

The operation of the process will be apparent from the illustrativeexamples wherein all parts and percentages are by weight.

Example 1 A copolymer of 97 percent vinylidene chloride and 3 percentacrylonitrile was fabricated into a continuous coherent fused film bythe continuous localized coagulation of a latex of said polymer followedby washing, slitting, drying, and fusing. Each tape was 0.0017 inchthick and slit to inch width. The fused but unoriented tapes were passedover snubbing rolls maintained at 30 C. and operated with a peripheralspeed of 24 feet per minute. The tapes were then passed overintermediate snubbers at 31 feet per minute. The tapes then passed overa pair of grooved, free-turning rolls, the first roll located 3 inchesfrom the intermediate snubbing rolls while the second grooved roll waslocated 3 inches from the first with the grooves offset /2 inch sidewaysfrom the grooves in the first. Each of the rolls was heated to C. Thewidth of the groove on the first roll was A inch at the surface and wasU-shaped to a depth of 1 inch. The groove in the second roll was inchwide at the surface, inch deep and was V- shaped with a rounded bottom.The tapes, after leaving the grooved rolls, passed over a third pair ofsnubbing rolls operated at feet per minute and then to spools at 107feet per minute. The resulting filament was a rolled structure having ahollow central portion with the void space amounting to approximately 60percent of the cross-sectional area of the filament. The tenacity of thefilament was about 2.7 grams per denier, the elongation 16 percent, andthe size of denier.

In a similar manner ribbons of a copolymer of about 96 percentvinylidene chloride and about 4 percent ethyl acrylate; of a linearpolyethylene; and of polypropylene were passed through the identicalsequence and a useful rolled filament resulted.

By the same procedure, rolled filaments of 1,100 denier were preparedfrom the indicated polymeric materials by increasing the width of theribbon and also by superposing 2 and 3 ribbons upon one another andpassing them through the indicated sequence.

Example 2 Tapes and ribbons, as prepared in Example 1, were passed overthe grooved rolls heated at 75 C. As the tape left the first groovedroll, a 40 denier nylon monofilament was inserted into the rolledfilament. The resulting filament was tightly rolled against the nylonmonofilamentary core.

In a similar manner, fiberglass multi-filament yarn, and polyethylenemonofilaments were inserted into the rolled tapes at the same point inthe procedural sequence.

What is claimed is:

1. A process for the preparation of rolled filamentary articlescomprising the passage of a continuous, coherent, unoriented, flexibleribbon of an organic, thermoplastic, resinous material in flat,undistorted form into first guide means, removal of said ribbon fromsaid first guide means so that a plane through the longitudinal axis ofsaid ribbon and perpendicular to the width of said ribbon is at an acuteangle to an extension of said plane of said ribbon entering said firstguide means, the passage of said ribbon through a second guide meansdisposed parallel to said first guide means so as to divert or todeflect said ribbon into a direction of travel substantially parallel toand finitely displaced from said plane of said ribbon entering saidfirst guide means while imparting a torque to said ribbon between saidfirst and second guide means to cause said ribbon to roll into afilament of an involute cross section having the original edges of saidribbon essentially parallel to the longitudinal axis of the filament andwhile maintaining suificient tension on said filament throughout theprocess to impart thereto orientation parallel to the longitudinal axisof said filament.

2. The process claimed in claim 1 wherein said organic, thermoplastic,resinous material is a normally crystalline vinylidene chloride polymer.

3. The process claimed in claim 2 wherein said normally crystallinevinylidene chloride polymer is a copolymer of from 92 to 99 percentvinylidene chloride and from 8 to 1 percent acrylonitrile.

4-. The process claimed in claim 2 wherein said normally crystallinevinylidene chloride polymer is a copolymer of from 92 to 99 percentvinylidene chloride and from 8 to 1 percent of an alkyl acrylate.

5. The process claimed in claim 1 wherein said organic, thermoplastic,resinous material is a polyolefin.

6. The process claimed in claim 5 wherein said polyolefin is apolyethylene.

7. The process claimed in claim 5 wherein said polyolefin ispolypropylene.

8. The process claimed in claim 1 wherein a filamentary core material isinserted into the rolled filament at a point in the procedural sequencewhere said ribbon leaves the first guiding means.

9. The process claimed in claim 8 wherein said filamentary core materialis a polyethylene monofilament.

10. The process claimed in claim 8 wherein said filamentary corematerial is a nylon yarn.

11. The process claimed in claim 8 wherein said filamentary corematerial is a yarn of glass fibers.

12. The process claimed in claim 1 wherein said unoriented, flexibleribbon is not more than one inch in width and is from 0.001 to 0.005inch in thickness.

13. The process claimed in claim 1 wherein said ribbon is warmed to atemperature below the softening temperature of said organic,thermoplastic, resinous material.

References Cited in the file of this patent UNITED STATES PATENTS1,585,622 Heany May 18, 1926 2,176,019 Cohoe Oct. 10, 1939 2,321,726Alderfer June 15, 1943 2,336,100 Jacque Dec. 7, 1943 2,363,457 AlderferNov. 21, 1944 2,407,926 Hamilton Sept. 17, 1946 2,589,514 Stalter Mar.18, 1952 2,612,679 Ladisch Oct. 7, 1952 2,674,025 Ladisch Apr. 6, 19542,825,624 Fry Mar. 4, 1958 2,829,421 Hanson Apr. 8, 1958 2,858,186 FrostOct. 28, 1958 2,918,784 Faircloth Dec. 29, 1959

1. A PROCESS FOR THE PREPARATION OF ROLLED FILAMENTARY ARTICLESCOMPRISING THE PASSAGE OF CONTINUOUN, COHERENT, UNORIENTED, FLEXIBLERIBBON OF AN ORGANIC, THERMOPLASTIC, RESINOUS MATERIAL IN FLAT,UNDISTORTED FORM INTO FIRST GUIDE MEANS, REMOVAL OF SAID RIBBON FROMSAID FIRST GUIDE MEANS SO THAT A PLANE THROUGH THE LONGITUDINAL AXIS OFSAID RIBBON AND PERPENDICULAR TO THE WIDTH OF SAID RIBBON IS AT AN ACUTEANGLE TO AN EXTENSION OF SAID PLANE OF SAID RIBBON ENTERING SAID FIRSTGUIDE MEANS, THE PASSAGE OF SAID RIBBON THROUGH A SECOND GUIDE MEANS,DISPOSED PARALLEL TO SAID FIRST GUIDE MEANS SO AS TO DIVERT OR TODEFLECT SAID RIBBON INTO A DIRECTION OF TRAVEL SUBSTANTIALLY PARALLEL TOAND FINITELY DISPLACED FROM SAID PLANE OF SAID RIBBON ENTERING SAIDFIRST GUIDE MEANS WHILE IMPARTING A TORQUE TO SAID RIBBON BETWEEN SAIDFIRST AND SECOND GUIDE MEANS TO CAUSE SAID RIBBON TO ROLL INTO AFILAMENT OF AN INVOLUTE CROSS SECTION HAVING THE ORIGINAL EDGES OF SAIDRIBBON ESSENTIALLY PARALLEL TO THE LONGITUDINAL AXIS OF THE FILAMENT ANDWHILE MAINTAINING SUFFICIENT TENSION ON SAID FILAMENT THROUGHOUT THEPROCESS TO IMPART THERETO ORIENTATION PARALLEL TO THE LONGITUDINAL AXISOF SAID FILAMENT.